Dual orifice impingement injector

ABSTRACT

An injector head having nozzle assemblies with each assembly being formed with dual coaxial orifices. Streams formed by dual orifices of different propellants being directed to impinge at a point within a propellant mixing zone. Each nozzle assembly of dual orifices maintaining by a momentum exchange between the coaxial streams a single stream of its respective propellant. A plurality of dual orifices can be located about the face of an injector head and arranged to impinge, for example, in a triplicate pattern.

United States Patent Mitchell et al.

[ 51 June 6,1972

[54] DUAL ORIFICE IMPINGEMENT INJECTOR [72] inventors: James P. Mitchell, North Palm Beach; Allan R. Cohen, Palm Beach Gardens,

both of Fla.

I73] Assignec: United Aircraft Corporation, East Hartford, Conn.

[22] Filed: lflay 5,1967

[21] Appl. No.: 636,551

Related 0.8. Application Data [63] Continuation of Ser. No. 426,71 1, Jan. 15, 1965.

[52] US. Cl. ..60/258, 60/39.74 A [51] Int. Cl ..F02k 9/02 [58] Field of Search ..60/240, 258; 239/404, 423,

[56] References Cited UNITED STATES PATENTS 2,379,161 6/l945 Kraps ..239/404 2,616,254 1 1/1952 Mock ..60/39.28 2,703,260 3/1955 Olson et al.. ...239/424 2,979,891 4/1961 Widell ..60l240 3,039,701 6/1962 Carlisle.... ....239/404 3,098,353 7/1963 Abild ..60/240 3,122,885 3/1964 Heidmann ..'.60/258 Primary ExaminerSamuel Feinberg Attorney.lack N. McCarthy [57] ABSTRACT 8 Clains, 13 Drawing Figures PATENTEDJUH 61912 sum 2 or 6 M Fa Z? Zea/v7 PATENTEUJUH 6 I972 SHEET 8 [IF 6 F062 JUP/ Z Y jay LIV/ P4 V 4 5% 2 7 r W wflfiw My 2% f. M ud Y 5 DUAL ORIFICE IMPINGEMENT INJECTOR This application is a continuation of Ser. No. 426,711, filed Jan. 15, 1965.

This invention relates to an injector head having dual orifices for each propellant with valving to provide a throttling capability.

An object of this invention is to provide an injector head which will do away with the problem of decreasing injection velocity and consequently combustion instability that occurs with a fixed area injector at low thrust. This injector head will maintain high propellant injection velocities required for stable, efficient combustion, at low thrust and over a wide thrust range by a momentum or energy exchange between a high velocity primary stream and a'low velocity secondary stream. The flow split between primary and secondary orifices is controlled so that the average injection velocity of the total propellant flow is always high enough to effect good propellant mixing. The primary flow is provided with sufficient pressure drop to flow at a high velocity at all levels of thrust while the velocity of the secondary flow decreases with decreasing thrust levels.

Another object of this invention is to provide an injector head having injector units with nozzle assemblies in which the low thrust primary orifice and the high thrust secondary orifice are concentric with each other. The primary orifice being in the center while the secondary orifice forms an annular orifice around it.

A further object of this invention is to provide an injector head which will do away with heating problems encountered with nonfiowing passages.

Another object of this invention is to provide an injector head which can be throttled to low flows, 2-10 percent of its maximum thrust.

A further object of this invention is to provide for flowing a small amount of propellant through the high thrust orifices for cooling if it is required during throttle operation.

7 Another object of this invention is to provide an injector unit wherein during throttle operation the flow from the high thrust orifice will be pulled" by the flow from the low thrust opening to provide good mixing of both streams.

A further object of this invention is to provide an injector head that will permit wide thrust variations with fixed area injector units.

Another object of this invention is to provide an injector head which provides thrust variations without having moving parts in the hot gases adjacent to the combustion chamber.

Other objects and advantages will be apparent from the specification and claims and from the accompanying drawings which illustrate embodiments of the invention.

FIG. 1 is a view showing the injector head in combination with a rocket nozzle. I

FIG. 2 is a schematic perspective view of the injector head with a section cut away for clarity.

FIG. 3 is a view of the face of the injector showing the triplet entrance of each unit with a section broken away.

FIG. 4 is a view taken along the line 4-4 of FIG. 3.

FIG. 5 is a sectional view taken along the line 55 of FIG. 4 showing the inner primary distribution system.

FIG. 6 is a sectional view taken along the line 6-6 of FIG. 4 showing the inner secondary distribution system.

FIG. 7 is a sectional view taken along the line 7--7 of FIG. 3 showing the connection of the oxidizer secondary manifold to the injector head.

FIG. 8 is an enlarged view of the nozzle insert for one propellant.

FIG. 9 is an end view of FIG. 8.

FIG. 10 is an enlarged view of the nozzle insert for another propellant.

With reference to FIG. 1, a rocket 2 is shown having an injector head 4 connected to a nozzle 6. A clamp 8 fixes the two outer parts 10 and 12 of the injector head together. While no means have been shown, the nozzle 6 can be fixed in relation to the injector head by any well known means. In one construction, the end of the nozzle 6 adjacent the injector head could be formed with the part 12 thereon so that the clamp 8 would then serve to maintain the injector head in place. Secondary propellant manifolds l4 and 16 are shown attached, respectively, by pipes 18 and 20 to the rear of the injector head. 1

'The injector head 4 as shown is comprised of a plurality of injector units 22 formed in an inner body 24 (see FIG. 2). Each injector unit 22 includes three cooperating nozzle assemblies 23A, 23B and 23C. Each nozzle assembly has an orifice 30 on the face 26 of the body 24 which forms the rear of the combustion chamber 28 of the main nozzle 6. Each injector unit 22 has a group of three cooperating orifices 30A, 30B and 30C. The number of injector units 22 incorporated in an injector head depends on the design of the rocket. If a large rocket is built for high thrust, a large number of injector units 22 would be employed and for a rocket of lower thrust rating, fewer injector units 22 would be used.

As seen in FIGS. 2 and 7,'each injector unit 22 has three holes 32, 33 and 34 drilled from the rear of the inner body 24 with each hole terminating respectively in the orifices 30A, 30B and 30C on the face of the body. The holes 32 and 34 are placed at an angle on each side of the opening 33 which is fonned perpendicular to the face 26 of the body 24. While this angle can be varied, an injector head was tested using an angle of 30.

To provide each noule assembly 23 with two orifices opening into the combustion chamber 28, an insert member 40 is positioned in the forward half of the holes 32 and 34 and in insert member 42 is positioned in the forward part of hole 33. The only difference between these insert members 40 and 42 is their length and the sizes of the orifices 44 and 46, respectively, at their tips. A passageway 48 connects the rear of the member 40 with its orifice 44 and a passageway 50 connects the rear of member 42 with its orifice 46. v

The forward end of the holes 32 and 34.are each formed having an inner conical face. 52. which cooperates with its respective orifice 30A or 30C. Each insert member 40 has three guide ribs 54 which are located at the orifice end and they engage its cooperating hole 32, or 34, to center the stem 56. This forms an annular passage between the hole 32 or 34 and the cooperating stem 56. The insert member 40 has an outer conical face 58 located between the ribs 54 and the tip of the insert which projects-into the inner conical face 52. This outer conical face 58 is formed having the same approximate angular slant as the inner conical face 52 and is spaced therefrom to form an annulus which is concentric with the orifice 44 at the tip of the insert member 40.

The rear end of the insert member 40 has an enlarged portion 60 which threadably engages its cooperating hole 32, or 34, at approximately mid-point of the body 24. While this enlarged portion 60 is threaded it is also fixed in position. This can be done by brazing. Further, this insert may have only an unthreaded enlarged portion which snugly fits its hole, 32, or 34, and it can then be brazed or use a mechanical seal for fix- It can be seen that any flow entering the annular passage between the hole 32, or 34, and the cooperating stem 56 will pass the ribs 54, and flow through the annulus formed between the conical faces 52 and 58 and out the respective orifice 30A or 30C.

The nozzle assemblies 23A and 23C are completed by the insertion of a plug 76 in the rear end of the holes 32 and 34. While each plug is shown threaded in its hole it is also fixed. This may be done by brazing. Further, the plugs can merely have a snug fit and brazed or use a mechanical seal. These plugs are located in the holes so as to permit a chamber between the front face of the plug 76 and the rear face of the enlarged portion 60 of the insert member 40.

It can be seen that any flow entering the chamber between plug 76 and enlarged portion 60 of insert member 40 will enter passageway 48 and pass therethrough and flow out orifice 44 and its respective orifice 30A, or 30C, the end of the insert member 40 being recessed a short distance from the face 26 of the body 24. f

The forward end of the hole 33 is formed having an inner conical face 62 which cooperates with its respective orifice 308. Each insert member 42 has three guide ribs 64 which are located at the orifice end and they engage its cooperating hole 33 to center the stem 66. This forms an annular passage between the cooperating hole 33 and the stem 66. The insert member 42 has anouter conical face 68 located between the ribs 64 and the tip of the insert which projects into the inner conical face 62. This outer conical 'face 68 is formed having the same angular slant as the inner conical face 62 and is spaced therefrom to form an annulus which is concentric with the orifice 46 at the tip of the insert member 42. The angular slant of conical faces 52, 58, 62 and 68 is approximately as shown with the center line of the insert.

The rear end of the insert member 42 has an enlarged portion 70 which threadably engages its cooperating hole 33 at approximately mid-point of the body 24. While this enlarged portion 70 is threaded, it is also fixed-in position. This can be done by brazing as before. Further, this insert may also have only an unthreaded enlarged portion which snugly fits its hole 33, and it can then be brazed or use a mechanical seal for fixing. It can be seen that any flow entering the annular passage between the hole 33 and the cooperating stem 66 will pass the ribs- 64 and flow through the annulus formed between the conical faces 62 and 68 and out the respective orifice 308.

.The nozzle assembly 23B is completed by the insertion of a plug'78 in the rear end of the hole 33. While each plug is shown threaded in its hole, it is also fixed. This may be done by brazing. Further, the plugs may have a snug fit and brazed or use a mechanical seal. This plug is located in the hole so as to permit a chamber between the front face of the plug 78 and the rear face of the enlarged portion 70 of the insert member 42. The chamber of nozzle assembly 238 is located on approximately the same plane in body 24 as the similar chambers of nozzle assemblies 23A and 23C of each injector unit.

-'It can be seen that any flow entering the chamber between plug 78 and enlarged portion 70 of insert member 42 will enter-the passageway 50 and pass therethrough and flow out the orifice 44 and itsrespectiveorifice B, the end of the insert member 42 being recessed a-short distance from the face 26 of the body 24. Y I

The three cooperating nozzle assemblies 23A, 23B and 23C of each injector unit22 provide dual orifices for the propellant injected through that nozzle assembly. One orifice being annular and surrounding acenter orifice formed as a single hole. The primary orifice of each nozzle assembly is considered to be the center orifice and the secondary orifice is considered to be the annular one. In the injector shown, the primary orifice has an area equal to approximately 2 percent of the secondary orifice area. The angular position of the nozzle assemblies 23A and 23C with respect to 238 provides for impingement of the propellants one on the other.

The injector shown has a triplet impingement pattern i.e. an oxidizer and a fuel were used with the fuel being directed to the nozzle assemblies 23A and 23C, and with the oxidizer being directed to the nozzle assembly 23B. While this combination was used, it is recognized that other combinations of propellants to an injector unit can be used. For example, the oxidizer could be directed to the nozzle assemblies 23A and 23C and a fuel could be directed to the nozzle assembly 23B. Other impingement patterns could also be obtained using the same basic principle set forth above.

In the injector head shown, the injector units 22 are arranged to form a pattern on face 26 such as shown in FIG. 3. A

plurality of rows of injector units are arranged with their triple orifices 30A, 30B and 30C being parallel to each other in each row and staggered between adjacent rows. The rows increase in number of injector units to a middle row.

A plurality of passages (see FIG. 6) extend inwardly from one half of the periphery of body 24 and a plurality of passages extend inwardly from the other half of the periphery of body 24 between each of passages 80. The passages 80 and 90 extend to a point adjacent the opposite periphery. Plugs 82 are placed in the drilled ends of the passages 80 to close the end and plugs 92 are placed in the drilled ends of passages 90 to close the end. These passages 80 and 90 are located on the same plane inbody 24 and this plane is located between the mid-point of body 24 and its face so that they will intersect the holes 32, 33 and 34 between the enlarged portions 60 and 70 and ribs 54 and 64, respectively, of the insert members 40 and 42 when they are in place.

The injector units are staggered between adjacent rows so that the intermediate passages 80 between the two small end passages 80 are connected to holes .32 and 34 of adjacent rows. The passages 90 merely extend down each row and intersect the holes 33.

The passages 90 are fed by a secondary manifold 16 which has pipes 20 extending therefrom into the rear of, the body 24 to meet with passages 94 which extend to the blocked ends of passages 90. Manifold 16 is connected-to a first propellant supply in a manner to be hereinafter described. It is noted that some of the passages 94 have been formed rectangular in shape to provide a desired area. The passages 80 are fed by the manifold 14 which has pipes l8extending therefrom into the passages are unblocked and extend into a groove formed on each half of the periphery. A groove 102 is formed around the periphery connecting the ends of passages and groove 1 12 extends around the other half of the periphery connecting the ends of passages 110. These passages 100 and extend to a point adjacent the opposite periphery. These passages 100 and 1 10 are located on the same plane in body 24 and this plane is located between the mid-pointof body 24 so. that they will intersect holes 32, 33 and 34 at the chambers between the plugs 76 and 78 and enlarged portions 60 and 70, respectively, of the insert members 40 and 42. Since the grooves 102 and: 112 are on the same plane, they are separated from each other by partitions 101 and 103 at eachend thereof. 7

When the injector head is mounted as shown in FIG. 1, the outer part 10 when clamped to the part 12, which is fixed to the rocket, forms a primary manifold with each of the grooves 102 and 112. The primary manifold A formed by part 10. and groove 102 is connected by a pipe 106 to the first propellant supply in a manner to be hereinafter described. The primary manifold B formed by the groove 112 and the part 10 is connected by a pipe 116 to the second propellant supply in a manner to be hereinafter described.

As shown in FIG. 12, a propellant supply 200 has its output directed to a propellant control valve 202 by a conduit 204. The outlet of the propellant control valve 202 is connected to (l) the pipe 106 connected to primary manifold A and (2) to the inlet of a flow divider valve 208. The outlet of the flow divider valve is connected to secondary manifold 16 by a conduit 210. A propellant supply 300 has its output directed to a propellant control valve 302 by a conduit 304. The outlet-of the propellant control valve 302 is connected-to (l) the pipe 116 which is connected to primary manifold B and (2) to the inlet of a flow divider valve 308. The outlet of the flow divider valve is connected to secondary manifold 14 by a conduit 310.

The propellant control valves 202 and 302 regulate the total flow from the propellant supplies 200 and 300, respectively, while the flow divider valves 208 and 308 regulate the flow split between primary manifolds .A and-B and secondary manifolds 16 and 14, respectively. The propellant control, valves 202 and 302 control the total flow to both primary and secondary manifolds for both propellants and control the thrust of the engine from its minimum to maximum thrust range. The control valves 202 and 302 are linked to move together for thrust control by a linkage 250. This linkage is adjustable in order to control the mixture ratio between propellants.

For both propellants, good combustion stability and efficiency are maintained by controlling the flow split with the flow divider valve between the primary and secondary manifolds, and therefore, the primary and secondary orifices of the nozzle assemblies, so that the average injection velocity of the total propellant flow is always high enough to effect good propellant mixing. The flow through the primary system of propellants is provided with sufficient pressure drop to flow at a high velocity at all levels of thrust; the velocity of the flow through the secondary system of propellants decreases with decreasing thrust levels. At low thrust levels, the stream from the primary orifice pumps or carries the stream from the secondary orifice to the propellant mixing zone.

At low thrust levels, the divider valve of each propellant is set so that the flow area is small and thus the flow is split approximately evenly between the primary and secondary orifices. As high thrust level increases, in response to opening of the control valves, the divider valves open up and thus most of the propellant flow is through the secondary orifice.

it is to be understood that the invention is not limited to the specific forms herein illustrated and described, but may be used in other ways without departure from its spirit as defined by the following claims.

We claim:

1. In combination, an injector having a body, said body having an injector face, a propellant mixing zone downstream of said face, a plurality of nozzle assemblies located in said body, a first nozzle assembly for a first propellant having first coaxial dual orifices formed with relation to said face to maintain by a momentum exchange between the coaxial streams a single stream of first propellant to the propellant mixing zone, a second noule assembly for a second propellant having second coaxial dual orifices formed with relation to said face to maintain by a momentum exchange between the coaxial streams a single stream of second propellant to the propellant mixing zone, said first and second nozzle assemblies having the axes of their dual orifices positioned to have impingement of said stream of first propellant and said stream of second propellant in said propellant mixing zone, said first and second coaxial dual orifices each comprising a central primary orifice and an outer larger secondary orifice therearound, each of said first and second coaxial dual orifices forming an ejector for injecting a stream, the area of said primary orifice being approximately 2 percent of the area of said secondary orifice.

2. An apparatus as set forth in claim 1 having in combination therewith, first conduit means connected to the central primary orifice of the first coaxial dual orifices, second conduit means connected to the larger secondary orifice of the first coaxial dual orifices, third conduit means connected to the central primary orifice of the second coaxial dual orifices, fourth conduit means connected to a larger secondary orifice of the second coaxial dual orifices, a first propellant supply, a second propellant supply, first valved means for controlling flow from said first propellant supply to said first and second conduit means, second valved means for controlling flow from said second propellant supply to said third and fourth conduit means, third valved means in said second conduit means for dividing the flow between said first and second conduit means, fourth valved means in said fourth conduit for dividing the flow between said third and fourth conduit means.

3. An apparatus as set forth in claim 2 wherein said first and second valved means are linked together to coordinate their movement and maintain a liquid mixture ratio between the first propellant and second propellant.

4. An apparatus as set forth in claim 3 wherein the third valved means is connected to said first valved means so that at low flow settings of said first valved means said second valved means is set with its flow area small and at higher flow settings of said first valved means said second valved means is open further with a greater proportion of flow going through the larger orifice, and the fourth valved means is connected to said second valved means so that at low flow settings of said second valved means said fourth valved means is set with its flow area small and at higher flow settings of said second valved means said fourth valved means is open further with a greater proportion of flow going through the larger orifice.

5. In combination 1. a propellant injector having a body,

a. said body having an injector face,

b. said body having a plurality of noule assemblies located therein for injecting a plurality of propellants,

2. a propellant mixing zone downstream of said face, 3. each of said nozzle assemblies for a propellant having:

a. a first elongated hole having an end opening onto said face,

b. a member positioned with one end in said first elongated hole,

c. said member having a second elongated hole therein opening onto said end as a first orifice,

d. said member positioned in said first elongated hole forming an annular orifice with said hole,

e. said member having a second elongated hole being positioned in said first elongated hole to form an ejector whereby a high velocity stream through said second elongated hole will pump a low velocity flow through the annular orifice formed therearound by a momentum exchange as a stream for impingement with a stream of another propellant in said propellant mixing zone,

f. said first orifice having a high velocity propellant flow passing therethrough during operation,

g. said annular orifice having a propellant flow passing therethrough which has a low velocity with relation to said first orifice so that the stream from the first orifice pumps the stream from the annular orifice through the injector face, and

h. said first orifice having an area which is approximately 2 percent of the area of the cooperating annular orifice.

6. An apparatus as set forth in claim 5 wherein the end of said first elongated hole tapers inwardly forming a reduced exit portion and the member positioned with one end in said first elongated hole forming an annular orifice with the reduced exit portion of the first elongated hole.

7. In combination:

l. a rocket having a propellant injector, a combustion chamber and associated exhaust nozzle,

2. said propellant injector having a body,

a. said body having an injector face, 7

b. said body having a plurality of nozzle assemblies located therein,

3. each of said nozzle assemblies for a propellant having:

a. a first elongated hole having an end opening onto said face,

b. a member positioned with one end in said first elongated hole,

c. said member having a second elongated hole therein opening onto said end as a first orifice,

d. said member positioned in said first elongated forming an annular orifice with said hole,

e. said member having a second elongated hole being positioned in said first elongated hole to form an ejector whereby a high velocity stream through said second elongated hole will pump a low velocity flow through the annular orifice formed therearound by a momentum exchange for impingement with a stream of another propellant in said combustion chamber,

f. said first orifice having an area which is approximately 2 percent of the area of the cooperating annular orifice,

4. a propellant supply,

hole

5. means for connecting said propellant supply to said first elongated hole and to said second elongated hole so that the propellant will pass through said first orifice and annular orifice,

6. said connecting means including control means for regulating the flow of propellant to the combustion chamber and therefore control the thrust level of the rocket engine, said flow through said first orifice being maintained at a high velocity at all thrust levels while the velocity of the flow through the annular orifice is varied as changes in thrust level are made, and

7. when said annular orifice has propellant flows therethrough at low thrust levels the high velocity stream from the first orifice pumps by means of momentum exchange the stream from the annular orifice into the combustion chamber.

8. A dual orifice impingement injector unit having in combination, a body, said body having an injector face, a plurality of nozzle assemblies located in said body, one of said assemblies including a first elongated hole extending from the interior of said body to the face, a first insert fixed in said first elongated hole, said first insert forming a first annulus with said body and extending approximately to the face of said body, said first insert having a first passageway therethrough, a second assembly including a second elongated hole extending from the interior of said body to the face, said second elongated hole extending at an angle to the first elongated hole, a second insert fixed in said second elongated hole, said second insert forming a second annulus with said body and extending approximately to the face of said body, said second insert having a second passageway therethrough, two grooves formed in the outer periphery of said body, an enclosure member extending around the periphery of said body and forming two closed manifolds with the two grooves, passageway means in said body connecting one manifold with said first passageway, second passageway means in said body connecting the other manifold with said second passageway, a first external manifold, a second external manifold, third passageway means connecting said first external manifold to said first annulus, fourth passageway means connecting said second external manifold to said second annulus.

i i i I 

1. In combination, an injector having a body, said body having an injector face, a propellaNt mixing zone downstream of said face, a plurality of nozzle assemblies located in said body, a first nozzle assembly for a first propellant having first coaxial dual orifices formed with relation to said face to maintain by a momentum exchange between the coaxial streams a single stream of first propellant to the propellant mixing zone, a second nozzle assembly for a second propellant having second coaxial dual orifices formed with relation to said face to maintain by a momentum exchange between the coaxial streams a single stream of second propellant to the propellant mixing zone, said first and second nozzle assemblies having the axes of their dual orifices positioned to have impingement of said stream of first propellant and said stream of second propellant in said propellant mixing zone, said first and second coaxial dual orifices each comprising a central primary orifice and an outer larger secondary orifice therearound, each of said first and second coaxial dual orifices forming an ejector for injecting a stream, the area of said primary orifice being approximately 2 percent of the area of said secondary orifice.
 2. An apparatus as set forth in claim 1 having in combination therewith, first conduit means connected to the central primary orifice of the first coaxial dual orifices, second conduit means connected to the larger secondary orifice of the first coaxial dual orifices, third conduit means connected to the central primary orifice of the second coaxial dual orifices, fourth conduit means connected to a larger secondary orifice of the second coaxial dual orifices, a first propellant supply, a second propellant supply, first valved means for controlling flow from said first propellant supply to said first and second conduit means, second valved means for controlling flow from said second propellant supply to said third and fourth conduit means, third valved means in said second conduit means for dividing the flow between said first and second conduit means, fourth valved means in said fourth conduit for dividing the flow between said third and fourth conduit means.
 2. a propellant mixing zone downstream of said face,
 2. said propellant injector having a body, a. said body having an injector face, b. said body having a plurality of nozzle assemblies located therein,
 3. each of said nozzle assemblies for a propellant having: a. a first elongated hole having an end opening onto said face, b. a member positioned with one end in said first elongated hole, c. said member having a second elongated hole therein opening onto said end as a first orifice, d. said member positioned in said first elongated hole forming an annular orifice with said hole, e. said member having a second elongated hole being positioned in said first elongated hole to form an ejector whereby a high velocity stream through said second elongated hole will pump a low velocity flow through the annular orifice formed therearound by a momentum exchange for impingement with a stream of another propellant in said combustion chamber, f. said first orifice having an area which is approximately 2 percent of the area of the cooperating annular orifice,
 3. each of said nozzle assemblies for a propellant having: a. a first elongated hole having an end opening onto said face, b. a member positioned with one end in said first elongated hole, c. said member having a second elongated hole therein opening onto said end as a first orifice, d. said member positioned in said first elongated hole forming an annular orifice with said hole, e. said member having a second elongated hole being positioned in said first elongated hole to form an ejector whereby a high velocity stream through said second elongated hole will pump a low velocity flow through the annular orifice formed therearoUnd by a momentum exchange as a stream for impingement with a stream of another propellant in said propellant mixing zone, f. said first orifice having a high velocity propellant flow passing therethrough during operation, g. said annular orifice having a propellant flow passing therethrough which has a low velocity with relation to said first orifice so that the stream from the first orifice pumps the stream from the annular orifice through the injector face, and h. said first orifice having an area which is approximately 2 percent of the area of the cooperating annular orifice.
 3. An apparatus as set forth in claim 2 wherein said first and second valved means are linked together to coordinate their movement and maintain a liquid mixture ratio between the first propellant and second propellant.
 4. An apparatus as set forth in claim 3 wherein the third valved means is connected to said first valved means so that at low flow settings of said first valved means said second valved means is set with its flow area small and at higher flow settings of said first valved means said second valved means is open further with a greater proportion of flow going through the larger orifice, and the fourth valved means is connected to said second valved means so that at low flow settings of said second valved means said fourth valved means is set with its flow area small and at higher flow settings of said second valved means said fourth valved means is open further with a greater proportion of flow going through the larger orifice.
 4. a propellant supply,
 5. means for connecting said propellant supply to said first elongated hole and to said second elongated hole so that the propellant will pass through said first orifice and annular orifice,
 5. In combination
 6. An apparatus as set forth in claim 5 wherein the end of said first elongated hole tapers inwardly forming a reduced exit portion and the member positioned with one end in said first elongated hole forming an annular orifice with the reduced exit portion of the first elongated hole.
 6. said connecting means including control means for regulating the flow of propellant to the combustion chamber and therefore control the thrust level of the rocket engine, said flow through said first orifice being maintained at a high velocity at all thrust levels while the velocity of the flow through the annular orifice is varied as changes in thrust level are made, and
 7. when said annular orifice has propellant flows therethrough at low thrust levels the high velocity stream from the first orifice pumps by means of momentum exchange the stream from the annular orifice into the combustion chamber.
 7. In combination:
 8. A dual orifice impingement injector unit having in combination, a body, said body having an injector face, a plurality of nozzle assemblies located in said body, one of said assemblies including a first elongated hole extending from the interior of said body to the face, a first insert fixed in said first elongated hole, said first insert forming a first annulus with said body and extending approximately to the face of said body, said first insert having a first passageway therethrough, a second assembly including a second elongated hole extending from the interior of said body to the face, said second elongated hole extending at an angle to the first elongated hole, a second insert fixed in said second elongated hole, said second insert forming a second annulus with said body and extending approximately to the face of said body, said second insert having a second passageway therethrough, two grooves formed in the outer periphery of said body, an enclosure member extending around the periphery of said body and forming two closed manifolds witH the two grooves, passageway means in said body connecting one manifold with said first passageway, second passageway means in said body connecting the other manifold with said second passageway, a first external manifold, a second external manifold, third passageway means connecting said first external manifold to said first annulus, fourth passageway means connecting said second external manifold to said second annulus. 